1. Field of the Invention
This invention relates to flexible structures having a broad range of utility. More specifically, the present invention relates to a flexible structure, which may find application as a tent or shelter, among other things, being of a type having at least one pole or rod maintained under tension in a selected shape, and a flexible member associated therewith, the structure exhibiting improved strength and rigidity in response to external loading forces, such as wind, rain, etc.
2. Description of the Prior Art
Convex multi-poled tent structures are described in U.S. Pat. Nos. 3,986,519, 4,099,533, 4,265,260, and 4,414,993, all of which are commonly assigned to the assignee of the present invention, and all of which are incorporated herein by reference as if repeated verbatim. U.S. Pat. Nos. 3,986,519 and 4,099,533 both disclose dome-like structures composed of a plurality of pole or rod elements maintained under tension in a generally arcuate shape, and an underlying membrane. Each structure includes at least two intersecting sets of such pole or rod elements. The rod or pole elements are held in fixed relationship at intersections by fittings secured to the underlying flexible membrane or sheath. The underlying membrane or sheath acts as a tension member to maintain the poles under tension. This structure, which employs the underlying membrane to tension the poles, lacks the added rigidity and strength of the structure of the present invention, which employs tension elements.
U.S. Pat. Nos. 4,265,260 and 4,414,993 disclose a flexible vault structure which similarly includes a plurality of deformable resilient poles that are held under tension in generally arcuate shape by an underlying fabric member. U.S. Pat. No. 4,265,260 discloses the use of fabric sleeves in addition to fittings for coupling the poles to the underlying fabric member. This structure similarly lacks the added rigidity and strength of the structure of the present invention, which includes additional tension elements.
Some multi-poled tent structures in the past have used internal guylines or similar structures located inside the enclosed space defined by the membrane in an effort to impart additional rigidity and strength to the structure. The guylines have generally extended between poles that define the structure and have consisted at most of two intersecting lines. Thus not only have the guylines failed to impart additional strength and rigidity to each pole, they have also interfered with the use of the enclosed space.
What is needed therefor and what has been invented is a flexible structure that exhibits improved rigidity and strength over prior art structures, and that overcomes the foregoing deficiencies associated with the prior art. More particularly, what is needed and what has been invented is a flexible structure comprising at least one deformable resilient pole with a tension web assembly coupled thereto in order to maintain the pole in a selected, e.g., a generally arcuate, shape under tension. The tension web assembly maintains the pole in its desired shape under tension and provides improved rigidity and strength when the structure is subjected to external load forces such as snow, wind, rain, etc. An underlying membrane may be coupled to the tension web assembly to provide a highly stable, rigid, and strong shelter structure, for example a tent.
Also provided is a method for making such a structure, including a method for maintaining one or more of a plurality of deformable resilient poles in a selected, e.g. generally arcuate, shape under tension such that the structure exhibits improved strength and rigidity in response to external forces.
The present invention broadly accomplishes the desired objects by providing a flexible structure comprising at least one deformable resilient pole, and at least one tension web assembly having one or more strut members and coupled to the pole to maintain it under tension in a selected, e.g., generally arcuate, shape. Preferably, the web assembly extends from a first point on the pole to a second point on the pole. More preferably, the distance from the first point to the second point is more than about 50% of the length of a tensioned, arcuately-shaped pole. Even more preferably, at least one web assembly generally extends from one end of the pole to another end of the pole.
Preferably, the flexible structure includes a plurality of tensioned generally arcuately-shaped poles and a plurality of tension webs coupled to the poles by means of hooks, sleeves or other means, such that each pole has at least one tension web associated therewith. The poles may, but not need be, arranged in a crossing pattern having a plurality of intersections, depending on the desired shape of the structure. The web assembly preferably comprises a relatively rigid material, e.g., a material comprising a plurality of tensile fibers oriented to resist undesired deformation of the poles, when subjected to external load forces.
A flexible member may be coupled to and supported by the web assembly to define a sheltered space. The flexible member is preferably a flexible membrane, such as tent fabric.